SU969465A1 - Method for cutting pipes - Google Patents

Description

(5) PIPE CUTTING METHOD

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The invention relates to the processing of metals by pressure and can be used. Used in mechanical engineering for cutting pipes in dies.

There is a known method of cutting pipes with flat knives moving in two mutually perpendicular directions, which consists in inserting one knife into the pipe cavity and cutting off the slot and the final separation of the pipe by the OTHER knife ij.

The disadvantage of this method is a reduction in the quality of the cutting surface, a decrease in the tool life at separation of pipes with increased wall thickness (more than 5 mm).

The purpose of the invention is to improve the quality of the billets and increase tool life.

With this purpose, in the method of cutting pipes with flat knives, moving in two mutually perpendicular directions, consisting in inserting one knife into the tube cavity and, ° cutting the slot and final separation of the pipe with another knife, preliminarily reduce the wall thickness of the pipe in her knife, cutting the slot. A reduction in the wall thickness of the pipe is produced by heating sections Q and k of the pipe with high frequency currents and subsequently exposing this area with a pointed pointed tool.

Reducing the wall thickness of the pipe 15 can be produced by milling.

Figure 1 shows the initial position of the workpiece and tools; Fig. 2 is a schematic of cutting a slot; Fig. 3 is a diagram of the separation of the tube 20 with a flat knife; in fig. - diagram of the process of heating the knife insertion site; Fig. 5 is a diagram of decreasing the wall thickness at the site where the milling knife is introduced; on. 6 - the same, the impact of a pointed pointed tool. A device for carrying out the method comprises a fixed matrix 1, a movable matrix 2, knives 3 and. To reduce the wall thickness of the pipe, cutters 5 or impact tools 6 are used. In the following case, inductor 7 fed with high-frequency currents can be used to heat the pipe. Cutting pipes with two flat blades moving in two mutually perpendicular directions is as follows. A tube 8 of square section with a wall thickness 5 is clamped by a force between the fixed 1 and the movable 2 matrices. The edges of the die 2, adjacent to the blades 3 and t, are cutting, so they need to ensure proper sharpening. After clamping the pipe 8, the knife 3 moves, the edge of which moves along, straight, located at a distance cf from the upper forming profile. The distance (G is somewhat larger than the wall thickness S. The knife 3 first, with a force Q, penetrates into the tube cavity at the insertion point Y, then turns the square cross-section angle upwards and removes the spline during further progress (Fig; 2). After the knife returns 3 The initial position starts its downward movement of the knife C for the final separation of the pipe 8. The knife 4 enters the 3 slot formed by the knife and first produces separation Q by the force Q on the side walls of the square profile of the pipe and then on this section of the profile. When the pipe is divided, the knife if, returns its original position

the matrix 2 releases the tube and the workpiece, which is removed.

As can be seen from the pipe cutting scheme with two flat blades moving in two mutually perpendicular directions, the cutting process begins with the knife 3 inside the closed cavity of the square pipe at the point; VJ. Any separation process is characterized by the occurrence of cracks between two cutting edges moving towards each other. During the insertion of the knife 3 into the cavity

It can be done by affecting this zone by a combination of heating operations and a sharp pointed instrument. First, at the point .N the zone is heated by high-frequency currents, as shown in Fig. 2, and then this heated zone is affected by the impact tool 6 Sfig ... The effect of decreasing strength is enhanced. Striking a pointed tool to a zone weakened by heating leads either to a significant decrease in wall thickness at point H, or to 5. 4, an unfavorable deformation pattern arises, since OTcyTctByeT has a sharp edge opposite to the edge of the knife 3. The sharp edge of the knife 3 in this case is opposed to the rigidity of the closed cross section of the pipe. If the stiffness of the cross section is insufficient, then the profile may lose stability and close. If the wall thickness is large, then the penetration of the knife 3 into the interior of the pipe is difficult in this case, the knife experiences the greatest bending stresses that cause it to break. As a rule, any penetration of the knife leads to a distortion of the profile of the pipe. FIG. 4 shows a decrease in the strength of the pipe wall due to heating at point N, where the knife 3 should penetrate into the inside of half the pipe 8, to which inductors 7 supply the high frequency currents with wall thickness S. (Inductors 7 at point N heat up the zone to 500 800 C and thereby reduce the strength of the wall by reducing the mechanical characteristics of the pipe material. The entire profile of the pipe retains its mechanical characteristics, and in the place where knife 3 must penetrate, mechanical characteristics are reduced, hence the condition of penetration of knife 3 into the floor the pipe has been improved. In Fig. 5, at the point 1M, the strength of the wall of the pipe 8 is reduced by reducing the thickness from S to 5. by milling .- For this, mills 5 are brought to the pipe, which remove part of the metal and thereby at the point of insertion knife 3 reduce the wall thickness to S. If the thickness S changes from 0 to 1/2 5, then the knife 3 penetrates inside the pipe 8 without visible distortion. The strength of the wall of the pipe 8 at the point N of penetration of the knife 3 decreases

the occurrence of a hole in this place without a perceptible distortion of the cross section of the pipe.

The proposed pipe cutting method allows to improve the quality of the obtained blanks and increase tool life.

Claims (3)

1. A method of cutting pipes with flat knives moving in two mutually perpendicular directions, which consists in inserting one knife into the pipe cavity and cutting it and the final separation of the pipe with another knife, in order to improve the quality of the resulting blanks and increase tool life, pre-produce a reduction in the wall thickness of the pipe at the site of introduction of a knife, cutting the slot. 2. The method according to claim 1, wherein the reduction in wall thickness of the pipe is performed by heating the pipe section with currents high frequency and subsequent impact on this area with a pointed pointed instrument. 3. The method according to claim 1, about tl and h a " u and in order to reduce the wall thickness, the pipes are produced by milling. Sources of information taken into account in the examination 1. Copyright certificate) USSR № 780990, cl. On 23 b 21/00, 1978.